Bonding wires are used in the manufacture of semiconductor devices for electrically interconnecting an integrated circuit and a printed circuit board during semiconductor device fabrication. Further, bonding wires are used in power electronic applications to electrically connect transistors, diodes and the like with pads or pins of the housing. While bonding wires were originally made from gold, nowadays less expensive materials such as aluminum are used. While aluminum wires provide very good electric and thermal conductivity, bonding of aluminum wires has its challenges.
Generally, bonding wires in the sense of the invention are optimized for use with high speed bonding tools, in which ball-bonding or second bonding (wedge bonding) is typically used to connect an end of the wire with a surface like a bond pad. In the case of aluminum based wires, wedge-wedge-bonding is predominantly used. Bonding wires have to meet specific demands in order to be compatible with bonding tools, at least within practicable process windows.
The term bonding wire may be understood to comprise all shapes of cross-sections and all usual wire diameters. Bonding wires with circular cross-section and thin diameters are possible, as well as thick bonding wires with circular cross sections or flatted cross sections for high power applications. Bonding wires with flatted cross sections are also called ribbons.
Some recent developments were directed to bonding wires having a core material based on aluminum as a main component due to its lower price compared with gold and other materials. Nevertheless, there is an ongoing need for further improving bonding wire technology with regard to the bonding wire itself and the bonding processes.